Echoing Turtle Soup

On a rainy, overcast night, a young international student returned from abroad. He dragged a heavy suitcase and walked into his home that he had not been to for a long time. The next morning, neighbors found him dead in the living room, his face wearing an expression of extreme terror, his eyes wide open, and he tightly clutched a yellowed airplane ticket in his hand. There were no signs of struggle in the house, no signs of outsider intrusion, and all doors and windows were intact. The only odd thing was that a bowl of turtle soup was placed on the table; the soup had gone cold and gave off a foul fishy stench.